Various types of ejector mechanisms have been used in the past to force material from a chamber. For example, it is known to use a pusher plate in a bucket for an excavator machine or in a bowl for a scrapper machine to force the material out of the bucket or bowl. These known pusher plates are normally controlled by a hydraulic cylinder so that when it is desired by the operator to eject the material, the operator merely operates a control valve which results in the hydraulic cylinder pushing the plate forward to force the material out of the bucket or bowl.
In strip mining applications, large excavating wheels have been used to remove overburden material so that coal can be harvested. These large wheel type excavating machines merely scoop up the overburden material in a plurality of individual scoops and as the individual scoops of the large wheel reach the topmost point of the wheel rotation, the overburden material falls out of the scoops onto a conveyor.
In a dredging application, an excavating wheel mechanism is used for removing silt, sand, mud or other sediment form the bottom of a body of water. One such dredging apparatus is disclosed in U.S. Pat. No. 5,907,915 and includes a floatation arrangement operative to float on the surface of the body of water, a frame structure mounted on the floatation arrangement, a silt excavating wheel mechanism rotatably mounted to the frame structure and operative to extract silt from under the body of water, and an ejector mechanism operative to urge the silt material from the silt retaining chambers associated with the wheel mechanism.
Typically, the dredging apparatus and its associated excavating wheel and ejector mechanisms are designed and constructed such that the dredging operation takes place in one predetermined direction such as in the forward direction of travel of the dredging apparatus. Since dredging only occurs in one direction, the excavating wheel mechanism is normally only operative in one direction of rotation, namely, either a clockwise or a counterclockwise direction of rotation, and the associated ejector mechanism likewise functions in conjunction with one direction of rotation of the excavating wheel.
It is therefore desirable to provide an ejector mechanism which is operable to urge soft material from the chambers of an excavating wheel regardless of the direction of rotation of the excavating wheel and which will enable a dredging apparatus to be operative in both the forward and reverse directions of travel.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.